The present invention relates to a refrigerator operating according to the Gifford-McMahon principle. Refrigerators are low temperature cooling machines in which a thermodynamic cycle takes place. The refrigerator includes a cylindrical work chamber disposed in a housing and further includes a displacement member which has a central regenerator and which, during operation, moves back and forth in the work chamber between two dead centers. The refrigerator further has connecting devices for a working gas including a port for a working gas at low pressure and a port for a working gas at high pressure, as well as gas control devices. A piston is fastened to the end face of the displacement member and has a smaller diameter than the displacement member. The piston cooperates with a cylinder into which merges a conduit for supplying working gas to the cylinder.
Refrigerators of the above-outlined type are used as the cold source in cryostats, cryopumps and the like.
The reciprocating movement of the displacement member generates dynamic forces, acceleration forces, inertia forces and the like which reach their maxima at the reversal points. These forces are transferred to the refrigerator housing and thus to devices coupled therewith. If the devices are sensitive to shocks, refrigerators of this type can often not be used.
It has already been proposed to damp the undesirable shocks and vibrations derived from the reciprocation of the displacement member. European Patent No. 19,426, to which corresponds U.S. Pat. No. 4,352,643, discloses the placement of a relatively expensive damping device between a cryopump and a shock sensitive instrument (for example, an electron microscope). European Patent Application No. 160,808, to which corresponds U.S. Pat. No. 4,642,995, discloses the placement of a flat spring within the work chamber. Such a spring, however, takes up a significant volume within the work chamber. This volume constitutes a dead space which reduces the efficiency of the refrigerator.